the problem with bicycles is they are not weather proof. if it’s cold or hot or stormy or hails, bicycles suck.

You can certainly use bicycles in many kinds of weather. Because this is a world-wide forum, we need to be a bit more specific about the weather conditions:

• You can ride bikes when it is raining, even heavily so. (Here in Germany, this happens less frequently than 20 years ago). Good rain clothes help with that.

• You can also ride a bike during stormy weather, though one needs to be a bit more careful. Said that, I have lived in Scotland and Northern Germany (which often has stormy weather in winter), and have been blown off my bike only a single time in, wait, over 40 years. And no, I am using bikes all the time - I never had a car.

• You can also ride bikes in quite cold weather - they are popular in Finland even in deep winter. What you do need to do then is to protect your extremities, especially hand and feet and also the face, against the cold. I use bar mittens (like these) for long rides in temperatures below - 10° C, and I find them super comfortable. If the road is a bit icy, studded tyres are great! In Germany, not much people use bikes in icy weather but this is mostly due to bike paths not cleaned from ice by the municipal road service, snow is melting and freezing again for days so that they can not be used in a safe way. In Finland, things are different, and bikes are used even in deep winter, as a preferred mode of transport.

• The limit is probably for extremely hot and humid temperatures, like are frequent in India, East-Asia, and some parts of Brazil. Here in Southern Germany, we rarely have above 33°C and perhaps 60% humidity, and being on the bike is still more comfortable than using a bus with poor ventilation, and much more comfortable than using a car without AC. Actually, I have now read several times of incidents in summer where AC was broken in very full trains, but never of any health damage a person took because of commuting by bike in hot weather. That's because the movement provides ventilation by the headwind, and ventilation cools (at that European level of humidity). (One more funny thing is that in Germany, AC in cars became only popular in the last 15 years or so. Now, some people are saying that on a bike, you "get too sweaty" for working in an office in Summer. That's funny, because entering a car without AC on a warm day was always like entering an oven, but nobody ever suggested to use the bike instead because it was less hot. All in all, that is just one of the many ways how people use made-up arguments to rationalize decisions that maximize their comfort, but are bad for their health).

then on top you’re excluding people who are not physically fit enough to use a bicycle for more than 5 minutes. and that includes people with disabilities of all kind.

I think you are making a mistake here, and this seems to affect the central point of your argumentation: You are assuming that somebody is demanding that a whole city uses either bikes or public transport, in an exclusive way. In reality, bikes and public transport are superb complements. Reasons for that include speed, economical factors, travel time, last-mile connections, urban life and more. Last not least because public transport in metros is two orders of magnitude more expensive than bikes, and therefore always limited in capacity. You can see this is way: Each time you are using a crowded metro, bus or street car, when you could as well go by bike, you are taking away a place from an perhaps elderly or ill person which really needs it.

In contrary, cars are not helpful for disabled and elderly people: Not only they can often not drive them, but they take away walking space and make their transport less safe.

so you still need public transport options anyway.

Of course, nobody was saying that one should exclusively use bikes! This is a strawman argument.

on days with bad weather, you can expect that at least 90% of people are gonna prefer public transport, so you have to size your buses and trams large enough to carry the full population anyways.

That depends a lot on culture and also on whether you have safe bike paths. Generally, normally rain, warm or cold weather does not impede cycling. What is making the difference is safe infrastructure and ways. One can see that clearly from the enormous rise of popularity of using bikes in Paris, once the necessary safe infrastructure was there.

so now you already have full public transport. at this point, why bother with bicycles, apart from the fun and physical exercise people get?

Again, bike and public transport are great complements - public transport will always be needed for elderly / disabled / ill people, and commuting or travelling large distances, and bikes are more economical, faster, and more convenient for shorter distances.

that’s why i conclude that bicycles are only for recreation/sports, not actually for mass transport.

Looks like you never have lived in a city or culture where the bike is a normal mode of transport. I guess you are American?

(And yes, I am aware that a community like this one which discusses alternatives to fossil-free transportation, might be frequented by poorly-informed people and also be targeted by astroturfing and 10-cent armies directed by the fossil fuel industry... one sees this in every discussion on climate protection.)